On 13/10/20 03:29, Sean Christopherson wrote:
@@ -3446,6 +3447,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
sync_lapic_to_cr8(vcpu);
+ svm->vmcb->control.asid = svm->asid;
Related to the above, handling this in vcpu_run() feels wrong. There really
shouldn't be a need to track the ASID. vmcb01 will always exist if vmcb02
exits, e.g. the ASID can be copied and marked dirty when loading vmcb02.
For new_asid(), it can unconditionally update vmcb01 and conditionally update
vmcb02.
Yeah, it is a bit ugly and it is only needed on processors without
flush-by-ASID. On those processors the ASID is used by KVM as a sort of
TLB flush generation count. A TLB flush should affect both VMCB01 and
VMCB02, and that's the reason to have a global ASID in struct vcpu_svm.
On processors with flush-by-ASID, currently we bump the ASID on every
physical CPU change. However even that is not needed, in principle
svm->asid should never change and we could also have different ASID01
and ASID02, similar to VMX. So: long term, svm->asid should only be
used only on processors without flush-by-ASID. kvm-amd however is not
quite ready for that.
Paolo
